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.Dd April 21, 2020
.Dt HWPSTATE_INTEL 4
.Os
.Sh NAME
.Nm hwpstate_intel
.Nd Intel Speed Shift Technology driver
.Sh SYNOPSIS
To compile this driver into your kernel
place the following line in your kernel
configuration file:
.Bd -ragged -offset indent
.Cd "device cpufreq"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for hardware-controlled performance states on Intel
platforms, also known as Intel Speed Shift Technology.
.Sh LOADER TUNABLES
.Bl -tag -width indent
.It Va hint.hwpstate_intel.0.disabled
Can be used to disable
.Nm ,
allowing other compatible drivers to manage performance states, like
.Xr est 4 .
Defaults to
.Dv Qq 0
(enabled).
.It Va machdep.hwpstate_pkg_ctrl
Selects between package-level control (the default) and per-core control.
.Dv Qq 1
selects package-level control and
.Dv Qq 0
selects core-level control.
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
values are available
.Bl -tag -width indent
.It Va dev.hwpstate_intel.%d.%desc
Describes the attached driver
.It dev.hwpstate_intel.0.%desc: Intel Speed Shift
.It Va dev.hwpstate_intel.%d.%driver
Driver in use, always hwpstate_intel.
.It dev.hwpstate_intel.0.%driver: hwpstate_intel
.It Va dev.hwpstate_intel.%d.%parent
The CPU that is exposing these frequencies.
For example
.Va cpu0 .
.It dev.hwpstate_intel.0.%parent: cpu0
.It Va dev.hwpstate_intel.%d.epp
Energy/Performance Preference.
Valid values range from 0 to 100.
Setting this field conveys a hint to the hardware regarding a preference towards
performance (at value 0), energy efficiency (at value 100), or somewhere in
between.
.It dev.hwpstate_intel.0.epp: 0
.El
.Sh COMPATIBILITY
.Nm
is only found on supported Intel CPUs.
.Sh SEE ALSO
.Xr cpufreq 4
.Rs
.%T "Intel 64 and IA-32 Architectures Software Developer Manuals"
.%U "http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html"
.Re
.Sh AUTHORS
This manual page was written by
.An D Scott Phillips Aq Mt scottph@FreeBSD.org .
